Thanks to New York’s industrial past, many of our waterways, including the Gowanus Canal, Newtwon Creek, and the Hudson River are horribly polluted — in fact, all three of those have been named Superfund sites, putting them among the most toxic sites in the nation. One of the biggest problems in the Hudson River is coal tar, a nasty substance notoriously hard to remove. For the last 18 months, engineers have been testing a new way to removed the pollutants — by placing mattress-sized “sponges” in the Hudson River to absorb toxins.